Item specifics
Description
CH340 USB to TTL Module Product Overview
The CH340 USB to TTL module is a serial converter tool based on the original CH340G chip, enabling bidirectional data communication between USB and TTL serial interfaces. It is the officially recommended USB-to-TTL solution by STC, compatible with the full range of STC microcontrollers without compatibility issues caused by different drivers or computers. The module supports dual voltage output of 5V and 3.3V, switchable via jumper caps. Equipped with PWR power indicator and TXD/RXD communication indicators for intuitive status monitoring. Widely used for STC/51 microcontroller programming, router upgrades, set-top box flashing, hard drive maintenance, and embedded development debugging.
CH340 USB to TTL Module Core Features
Original CH340G Chip, Stable and Reliable： Uses the original CH340G chip from Nanjing Qinheng Microelectronics, supporting USB 2.0 full-speed transmission (12Mbps) and compatible with USB 1.1. This chip is STC’s officially recommended USB-to-TTL solution, eliminating compatibility issues caused by different drivers or computers.
Dual Voltage Output, Compatible with 3.3V/5V Systems： Provides both 3.3V and 5V power outputs, selectable via jumper caps (1-2 short for 5V, 2-3 short for 3.3V). TTL logic level adapts to the supply voltage, matching different target devices.
Wide Baud Rate Range, Flexible Configuration： Supports baud rates from 300bps to 2Mbps, covering most microcontroller and serial device communication needs. Configurable with 5/6/7/8 data bits, 1/2 stop bits, and various parity options.
Tri-Color Indicators, Clear Status at a Glance： Onboard PWR power indicator (red), TXD transmit indicator, and RXD receive indicator for intuitive status monitoring without additional instruments.
Full-Duplex Communication & Hardware Flow Control： Supports full-duplex communication for simultaneous transmission and reception. Provides RTS, CTS, DTR, DSR and other hardware flow control signals for various serial applications.
Plug-and-Play, Multi-OS Compatibility： Supports Windows 98/ME/2000/XP/Vista/7/8/10/11 (32/64-bit) and Server series. Drivers are Microsoft digitally signed for easy installation. Also compatible with Linux and macOS systems.
No External Crystal, Built-in Clock： The CH340G chip features an internal clock circuit, eliminating the need for an external crystal and simplifying peripheral circuit design.
Industrial-Grade Wide Temperature Range： Operating temperature range of -40℃ to +85℃, suitable for both industrial and consumer applications.
CH340 USB to TTL Module Applications
STC/51 Microcontroller Programming： Connects the computer USB port to STC series microcontrollers for program download and burning; the STC officially recommended solution.
Embedded System Development & Debugging： Provides serial debugging channels for Arduino, ESP8266, STM32, and other development boards.
Router/Set-Top Box Upgrades： Used for firmware upgrades and system maintenance on routers and network set-top boxes.
Satellite Receiver Flashing： Widely used for flashing and upgrading satellite receivers.
Industrial Equipment Serial Communication： Provides USB-to-serial communication capability for industrial control devices.
CH340 USB to TTL Module Key Advantages
STC Officially Recommended, Compatibility Assured： The CH340G is STC’s officially designated USB-to-TTL chip solution, perfectly compatible with the full STC microcontroller series, avoiding the compatibility issues common with PL2303 solutions.
Dual Voltage Design, One Board for Multiple Uses： No need to purchase separate voltage converters; one tool serves both 3.3V and 5V system debugging and programming needs.
Complete Indicators, Intuitive Debugging： PWR/TXD/RXD tri-color indicators make working status clearly visible without an oscilloscope.
Stable Drivers, Full Windows Support： Supports the full range of Windows systems from Windows 98 to Windows 11 (32/64-bit), with Microsoft digitally signed drivers for simple and stable installation.
Wide Baud Rate, Broad Applicability： Supports baud rates from 300bps to 2Mbps, covering applications from low-speed sensors to high-speed data transmission.
Industrial-Grade Quality, Stable and Durable： Uses original CH340G chip with an operating temperature range of -40℃ to +85℃, suitable for long-term stable operation.
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FAQ
1. What is the CH340 module, and how does it differ from the common CP2102 and FT232?
The CH340 is a USB‑to‑serial chip developed by Nanjing Qinheng Microelectronics, widely used in USB‑TTL converter modules. Compared to the CP2102, the CH340 typically requires manual driver installation on Windows 10/11, whereas the CP2102 may be recognized automatically. Compared to the FT232, the CH340 is far more affordable and is the most common solution on domestic development boards and download cables. Its greatest strengths are its outstanding cost‑effectiveness and its ability to operate reliably at both 3.3V and 5V logic levels, making it ideal for programming and debugging mainstream MCUs like Arduino, ESP32, and STM32.
2. What should I do if I get “Device not recognized” or “Driver installation failed” after plugging it into the PC?
This is the most common issue with the CH340. First, download the latest CH340 driver (CH341SER or CH340G driver) from the Qinheng website or the page where you purchased the module. The module must be unplugged before running the installer; plug it back in only after installation completes. If it still isn’t recognized, try a different USB cable—make sure it is a data‑capable cable, not a charge‑only one—and check that the USB port is working. When properly installed, the CH340 should appear in Device Manager under “Ports (COM & LPT)” as “USB‑SERIAL CH340 (COMx).”
3. How should I connect the TXD and RXD pins to my MCU? Why does the download fail even when the wiring seems correct?
This is the most error‑prone part. Remember the “cross‑connect” rule: the module’s TXD must connect to the MCU’s RXD, and the module’s RXD must connect to the MCU’s TXD. Two other common reasons for download failure are: ① the module’s VCC pin should be connected to the MCU’s supply voltage (3.3 V for a 3.3 V system, 5 V for a 5 V system) to ensure proper logic‑level matching; ② some MCUs (e.g., ESP32) require pulling IO0 low and resetting to enter download mode—in that case, the DTR/RTS pins on the CH340 can work with an auto‑download circuit to enable one‑click programming without manual button presses.
4. What is the difference between the 3.3 V and 5 V pins on the module? How should I power the module?
The CH340 chip itself is powered by the USB 5 V supply. The 3.3 V and 5 V pins on the module are output pins intended to provide temporary power to the MCU (e.g., during programming). If you do not need the module to power the target board during programming, simply connect GND, TXD, and RXD—the module and the target board can be powered independently, and the VCC pin remains unconnected. If you want the module to power the MCU, connect the module’s 3.3 V or 5 V pin to the MCU’s VCC, choosing the voltage appropriate for your MCU.
5. Which operating systems does the CH340 support? Do macOS and Linux require drivers?
CH340 requires a manual driver installation on Windows. On macOS and Linux, the CH340 is typically supported natively by the kernel (Linux kernels since version 3.x include a built‑in driver), and it should be recognized as soon as it is plugged in without any additional installation. However, on newer macOS versions, it may conflict with the system’s built‑in AppleUSBCHCOM driver; in that case you may need to unload the conflicting driver via Terminal or install a dedicated CH340 Mac driver. Check the Qinheng website for the latest compatibility notes before using it on a Mac.
6. Can this module be used to program STC microcontrollers? How is it different from a generic USB‑TTL module?
Yes. The CH340 module is actually the classic download cable for STC MCUs. Compared to a generic USB‑TTL module, an STC download cable usually adds a diode in series with the TXD line and a resistor in series with the RXD line to meet the requirements of the STC download circuit. This is why some modules are explicitly labeled as “STC download cables.” If your module lacks the diode, it can still be used, but you may need an extra cold‑start step (completely power‑cycling the MCU) during programming.
7. What is the maximum baud rate of the module? Can it reliably support 2 Mbps?
The CH340 chip nominally supports a maximum baud rate of 2 Mbps. In practice, stability depends on USB cable quality, driver version, and PCB layout. For the vast majority of applications—such as 921600 bps on STM32, or 115200/460800 bps on ESP32—the CH340 performs flawlessly. If you encounter data loss or garbled output at high speeds, try lowering the baud rate or switching to a higher‑quality shielded USB cable.
8. What are the DTR, RTS, CTS pins for? Do I need them for ordinary serial communication?
These are modem‑control signal pins. For ordinary serial communication (e.g., GPS modules, serial passthrough), you do not need to connect them—just use GND, TXD, and RXD. DTR and RTS are primarily used on Arduino, ESP32, and similar boards to work with an auto‑download circuit for “one‑click programming.” When the IDE initiates a download, these pins automatically assert the appropriate control signals to put the MCU into download mode, eliminating the need to manually press BOOT and RESET buttons.
9. Why is there such a large price difference between CH340 modules? What is the difference between the cheap and the more expensive ones?
The price differences mainly come from PCB quality, components, and additional features. Cheaper modules may use a minimal circuit (just the chip, crystal, and a few capacitors) without a power LED, without DTR breakout, and without transient‑voltage suppression. More expensive modules typically feature an ENIG (gold‑plated) PCB, a self‑resetting fuse, ESD protection diodes, full breakout of all signal pins, and possibly an on‑board 3.3 V LDO regulator. For everyday development and debugging, a basic module is entirely sufficient; if you are building a product or need high reliability, a better‑built module is recommended.
10. How can I make the CH340 module support RS485 or RS232 communication?
The CH340 is a TTL‑level serial chip and cannot be connected directly to RS485 or RS232 devices. For RS485, pair it with a TTL‑to‑RS485 converter module (such as MAX485 or SP3485). For RS232, pair it with a TTL‑to‑RS232 converter module (such as MAX232 or SP3232). The connection method is straightforward: cross‑connect the CH340’s TXD and RXD to the TTL side of the converter module; the other side of the converter can then be connected to the RS485 bus or the RS232 device.